JWSS Biology Chapter 1 Cells

3G3 Science (Biology) Chapter 1 Notes 1 JURONG WEST SECONDARY SCHOOL SECONDARY THREE – SCIENCE BIOLOGY Chapter 1: CELLS Learning Outcomes: Candidates should be able to: (a) identify (label) and state the functions of the following cell structures (including organelles) of typical plant and animal cells from diagrams, light micrographs and as seen under the light microscope using prepared slides and fresh material treated with an appropriate temporary staining technique: ● cell wall ● cell membrane ● cytoplasm ● nucleus ● cell vacuoles (large, sap-filled in plant cells, small, temporary in animal cells) ● chloroplasts (b) identify and state the functions of the following organelles from diagrams and electron micrographs: ● mitochondria ● ribosomes (c) compare the structure of typical animal and plant cells (d) explain how the structures of specialised cells are adapted to their functions (e.g. muscle cell – many mitochondria to supply more energy, root hair cell – large surface area of cell membrane for greater absorption, red blood cell – lack of nucleus allowing it to transport more oxygen) RECAP: 1. A cell is a unit of life. 2. All organisms are composed of one or more cells. 3. Each living cell consists of living material called protoplasm. a. Protoplasm of a cell is made up of three parts: cell surface membrane, cytoplasm and nucleus.

3G3 Science (Biology) Chapter 1 Notes 2 4. Most cells are too small to be seen with our eyes. We use light or electron microscopes to help us see the cells. a. Light Microscope ● Colour image ● Magnification ῀ x600 http://moziru.com/images/light-microscopy-clipart-labeled-11.gif b. Magnification ● One crucial parameter that all microscopes depends on is its magnification. ● Magnification is the extend to which an object is enlarged. ● Calculation of magnification o Magnification can be claculated in two ways and should be recorded as ONE decimal place. 1. Magnification provided by a light microscope can be calculated as: Magnification = magnification of eyepiece lens X magnification of objective lens 2. Magnification undergone by the specimen to produce the image/drawing can be calculated as: Magnification = Size of drawing (mm) / actual size of specimen (mm)

3G3 Science (Biology) Chapter 1 Notes 3 worked Example 1 a. What is the total magnification provided by a light microscope? b. 3.9 cm c. Electron Microscope ● Black and white image ● Magnification ῀ x500 000 Eyepiece X10 Objective lens X40 Magnification = magnification of eyepiece lens X magnification of objective lens (Substitute known values into equation) = = The actual length of the ant is 0.9cm. Calculate the magnification of the drawings. Magnification = Size of drawing (mm) / actual size of specimen (mm) (Substitute known values into equation) = =

3G3 Science (Biology) Chapter 1 Notes 4 (a) identify and state the functions of the following cell structures (including organelles) of typical plant and animal cells from diagrams, light micrographs and as seen under the light microscope using prepared slides and fresh material treated with an appropriate temporary staining technique: ● cell wall ● cell membrane ● cytoplasm ● nucleus ● cell vacuoles (large, sap-filled in plant cells, small, temporary in animal cells) ● chloroplasts ANIMAL CELL - DIAGRAM Cell surface membrane • Also known as plasma membrane • Is made up of lipids (fats) and proteins • Is partially permeable • Allows only some substances to pass through o Some examples are glucose, water, minerals etc (small substances) • Function: o Control substances entering or leaving the cell. Cytoplasm • Part of the protoplasm • Function: o Contains specialised cell structures called organelles such as mitochondria and ribosomes. o Site where most cell activities occur. (Function) Nucleus • Contains nucleolus and chromatin (made of DNA) • Surrounded by the membrane called the nuclear envelope. • Function: o Controls cell activities such as cell growth, cell division and repair of worn-out parts. o Contains DNA which stores genetic information. Vacuole • Numerous, small, temporary • Function: o Stores water and nutrients

3G3 Science (Biology) Chapter 1 Notes 5 ANIMAL CELL - PHOTOMICROGRAPH http://innolearn.weebly.com/uploads/2/5/9/3/25936499/166866785.jpg PLANT CELL - DIAGRAM Cellulose cell wall • Encloses the entire plant cell • Surrounds the plasma membrane • Protects the cell from injury • Gives the plant a fixed shape • Is fully permeable Large Central Vacuole/ Sap Vacuole • Contains a liquid called cell sap • cell sap contains dissolved substances such as sugars, minerals salts and amino acids • enclosed by a partially permeable membrane called tonoplast Chloroplast • Oval structures • Site (place) for photosynthesis • Contain green pigment called chlorophyll essential for photosynthesis • Chlorophyll traps light energy and is converted to chemical energy. This occurs in the presence of water and carbon dioxide, and produces glucose and oxygen.

3G3 Science (Biology) Chapter 1 Notes 6 PLANT CELL - PHOTOMICROGRAPH http://middletownhighschool.wikispaces.com/file/view/ch13f20.jpg/173915407/ch13f20.jpg (b) identify and state the functions of the following organelles from diagrams and electron micrographs: ● mitochondria ● ribosomes ANIMAL CELL – DIAGRAM https://upload.wikimedia.org/wikipedia/commons/0/0d/0312_Animal_Cell_and_Components.jpg

3G3 Science (Biology) Chapter 1 Notes 7 PLANT CELL - DIAGRAM RIBOSOMES MITOCHONDRIA https://biologyofcells2011.weebly.com/uploads/8/9/4/4/894 4187/7010596_orig.jpg http://cdn.biologydiscussion.com/wp- content/uploads/2016/07/clip_image007-20.jpg ● Small round structures either (1) attached to membrane of the endoplasmic reticulum (ER) OR (2) lie freely in the cytoplasm or mitochondria ● Function: o Needed for the synthesis (make) of protein in the cell ● Ribosomes attached to ER makes proteins that are transported out of the cell ● Small oval or sausage shaped organelles ● Function: o Aerobic respiration occurs in the mitochondria o During respiration, glucose is oxidised to release energy used to perform cell activities such as growth and reproduction DON’T WRITE PRODUCE ENERGY

3G3 Science (Biology) Chapter 1 Notes 8 ● Ribosomes that lie freely make proteins that are used in the cell Functions of the various organelles: No Organelle Functions 1 Chloroplast ● Site (place) for photosynthesis ● Contain green pigment called chlorophyll essential for photosynthesis 2 Cell surface membrane ● Control substances entering or leaving the cell. 3 Cellulose cell wall ● Protects the cell from injury ● Gives the plant a fixed shape 4 Cytoplasm ● Contains specialised cell structures called organelles such as mitochondria and ribosomes. ● Site where most cell activities occur. 5 Vacuole ● Stores water and nutrients (Animal) ● Contains a liquid called cell sap which contains dissolved substances such as sugars, minerals salts and amino acids (Plant) 6 Nucleus ● Controls cell activities such as cell growth, cell division and repair of worn-out parts. ● Contains DNA which stores genetic information. 7 Mitochondria ● Aerobic respiration occurs in the mitochondria ● During respiration, glucose is oxidised to release energy used to perform cell activities such as growth and reproduction 8 Ribosome a) Needed for the synthesis of protein in the cell (c) compare the structure of typical animal and plant cells ANIMAL CELL SIMILARITIES PLANT CELL Both hav